Changeset d241aae in mainline for uspace/lib/ext2/libext2_filesystem.c

Timestamp:

2011-02-15T19:24:38Z (14 years ago)

Author:

Martin Sucha <sucha14@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

ce13577

Parents:

1d6f507

Message:

Add support for reading ext2 block group descriptors

File:

• uspace/lib/ext2/libext2_filesystem.c (modified) (2 diffs)

uspace/lib/ext2/libext2_filesystem.c

@@ -34 +34 @@
  */
 
-#include "libext2.h"
+#include "libext2_filesystem.h"
+#include "libext2_superblock.h"
+#include "libext2_block_group.h"
 #include <errno.h>
 #include <libblock.h>
@@ -105 +107 @@
 
 /**
+ * Get a reference to block descriptor
+ * 
+ * @param fs Pointer to filesystem information
+ * @param bgid Index of block group to find
+ * @param ref Pointer where to store pointer to block group reference
+ * 
+ * @return              EOK on success or negative error code on failure
+ */
+int ext2_filesystem_get_block_group_ref(ext2_filesystem_t *fs, uint32_t bgid,
+    ext2_block_group_ref_t **ref)
+{
+        int rc;
+        aoff64_t block_id;
+        uint32_t descriptors_per_block;
+        size_t offset;
+        ext2_block_group_ref_t *newref;
+        
+        newref = malloc(sizeof(ext2_block_group_ref_t));
+        if (newref == NULL) {
+                return ENOMEM;
+        }
+        
+        descriptors_per_block = ext2_superblock_get_block_size(fs->superblock)
+            / EXT2_BLOCK_GROUP_DESCRIPTOR_SIZE;
+        
+        // Block group descriptor table starts at the next block after superblock
+        block_id = ext2_superblock_get_first_block(fs->superblock) + 1;
+        
+        // Find the block containing the descriptor we are looking for
+        block_id += bgid / descriptors_per_block;
+        offset = (bgid % descriptors_per_block) * EXT2_BLOCK_GROUP_DESCRIPTOR_SIZE;
+        
+        rc = block_get(&newref->block, fs->device, block_id, 0);
+        if (rc != EOK) {
+                free(newref);
+                return rc;
+        }
+        
+        newref->block_group = newref->block->data + offset;
+        
+        *ref = newref;
+        
+        return EOK;
+}
+
+/**
+ * Free a reference to block group
+ * 
+ * @param ref Pointer to block group reference to free
+ * 
+ * @return              EOK on success or negative error code on failure
+ */
+int ext2_filesystem_put_block_group_ref(ext2_block_group_ref_t *ref)
+{
+        int rc;
+        
+        rc = block_put(ref->block);
+        free(ref);
+        
+        return rc;
+}
+
+/**
  * Finalize an instance of filesystem
  *